Barometric damper



Jan. 16, 1951 M. W. CREW BAROMETRIC DAMPER Filed Aug. 29, 1945 IN V ENTOR.

.MORR/S I/L C/Pfl V Patented Jan. 16, 1951 BAROMETRIC DAMPER Morris W.Crew, Milwaukee, Wis., assignor to Perfex Corporation, Milwaukee, Wis.,a corporation of Wisconsin Application August 29, 1945, Serial No.613,347

8 Claims.

It has become common to provide furnaces with barometric dampers whichmaintain constant draft in the take-off flues. These dampers usuallyconsist of a vane which is pivoted offcenter and which is provided witha biasing weight, thereby responding to the difierence in pressurebetween the flue and atmosphere. As this pressure difference or draftincreases, the vane moves inwardly for permitting air to enter the flue,thereby tending to maintain the draft constant.

It has been found that dampersof this type usually work satisfactorilywhen new, but gradually become inoperative over a long period of time.The reason for this is that the bearings become dirty or rusty, thusrequiring a substantial force in order to move the damper blade. Inorder for the damper to maintain a fairly uniform draft it must bemovable by a very small force. Thus when the bearings become rusty ordirty the damper remains stationary, even though the draft may changeconsiderably.

The primary object of this invention is to provide a barometric orpressure operated damper which is not subject to loss of efficiency dueto age. This result is obtained by completely elimi- I mating the usualbearing type pivots and mounting the damper blade on spring 'hingeswhich flex to permit movement of the damper b1ade.

A further object of the invention is to provide an arrangement in whichthe damper blade is located between the spring hinges and stack so as toprotect the spring hinges from the products of combustion.

A further object of the invention is to provide an arrangement in whichthe spring hinges carry the weight of the damper blade in tension.

Other objects of the invention will appear from the followingdescription and the appended claims.

For a full disclosure of the invention, reference is made to thefollowing detailed description and to the accompanying drawings inwhich,

Fig. 1 is a front elevation ,of a barometric damper embodying theinvention;

Fig. 2 is a side sectional view taken on line 2-2 of Fig. 1;

Fig. 3 is an enlarged fragmentary sectional view showing the damper inclosed position; and

Fig. 4 is a view similar to Fig. 3 showing the damper in open positionReferring to the drawings, reference character I indicates a damperframe.This frame is formed with an opening 2 which receives a damperblade 3. As shown in Fig. 2, the inner 2 edges of the frame are turnedinwardly as at 4 to, provide for mounting the damper frame on a thimble(not shown), which in turn is mounted to a stack or flue (not shown).Extending inwardly from the damper frame is a bracket 5. This bracketmay be formed integral with the frame or may be a separate piecespot-welded to the frame as shown. Attached to this'bracket is a springhinge 6. In the embodiment of the in- Vention illustrated, the springhinge is secured to the bracket by screws 1. As shown in Fig. 3,thesescrews extend through holes in the bracket and spring hinge intothreaded engagement with a cross member 8. Located on the opposite sideof the damper frame is a similar bracket 9 which supports the upper endof a spring hinge Ill and which is also attached to the cross member 8.The lower ends of the spring hinges are secured to the damper frame asshown in Figs. 3 and 4. The lower end of the spring hinge 6 is shown asspaced from the damper blade 3 by a spacer ll, screws l2 passing throughthis spacer and through holes at the bottom of the spring hinge. Thesescrews threadedly engage an arcuate member [3 which extends upwardlyadjacent the spring hinge. The lower end of the spring hinge H] isfastened to the damper blade in this same manner and an arcuate member[4 is located adjacent this spring hinge.

The damper blade is shown as being biased to closed position by means ofa weight I5 which is threadedly mounted on a stud 16 attached to thedamper blade. Preferably a spring washer IT is attached to the nut andengages the stud so as to prevent unintentional rotation of the weight.

It will be apparent that the Weight l5 serves to bias the damper towardclosed position and that the combined weight of the damper blade and itsbiasing weight is carried by the springhinges in tension. Due to thespring hinges being located off-center with respect to the damper blade,a differential in pressure across the blade causes rotation of thedamper. Thus as the furnace draft increases, the difference in pressurecauses the damper to rotate clockwise, as seen in Figs.-2, 3, and 4. Asshown in Fig. 4, the flexure of the spring hinges is controlled by thearcuate members l3 and I4. These arcuate members limit the maximum.curvature of the spring hing-es and thus prevent these hinges from beingstressed beyond their elastic limit. In other words, these arcuatemembers serve to spread the flexing of the spring hinges over theirentire length instead of permitting the spring to yield only at itsweakest or most highly stressed point.

From the foregoing description it will be apparent that the presentinvention provides a damper construction in which the spring hinges areprotected from products of combustion and also in which the springhinges carry the damper and biasing weight in tension. This arrangement,in which the spring hinges carry the weight of the dampenand biasingweight in tension, permits the hinges to carry their load in the mostfavorable manner.

While a single embodiment of the invention." has been shown, it will beapparent that ,numer-.

.. blade, and a pair of spring hinges, one adjacent ous changes may bemade without departing from the spirit and scope of the invention. It isdesired therefore to be limited only by the scope of the appendedclaims.

What is claimed is:

1. In a damper constructionja frame having" an opening, a damper bladefor the o.pening, a.

cross member extending from side to side of the frame across saidopening, and-apair of spring hinges, one adjacent each end of the crossmem- "ber, each spring hinge having its upper end attached to-the crossmember and its lower end attached to the damper blade whereby the Weightof the damper blade is carried by the spring hinges in tension.

2. In a damper construction, a frame having an opening, a damperbladefor the opening, a cross member extending from side to side of theframe across said openingand a pair of spring hinges, one adjacent eachend of the cross member, each spring hinge having its upper end attachedto the cross member and its lower-end attached to the damper bladewhereby the weight of the damper blade is carried by the spring hingesin tension, and arcuate means adjacent the spring hinges for limitingthe curvature thereof. I

3. In a damper construction; a frame having an opening, a damper bladefor the opening, a cross member extending from side to side of the frameacross said opening, and a pair of spring hinges, one adjacent each endof the cross memberyeach spring hinge having its upper end-attached stothe cross member and its lower end attached to the damper blade wherebythe weight of the damper blade is carried -by the spring hinges intension, and arcuate means carried by the free ends of the spring hingesfor limiting the curvature of said spring hinges. I

4. In a barometric damper, in combination, a frame :formed with mountingmeans at its rear for mounting it tothe line of a furnace, said framebeing also formed with an opening, a damper blade in said opening, crossmember means extending across said opening from side .to side .of theframe and in front of the damper blade, and a pair of flat spring hingesattached to said cross member and to the front of said damper blade.

5.. In a barometric damper, in combination, a frame formed with mounting"means at its rear 'for mounting it to the flue of a furnace, saidframebeing also formed with an opening, a damper blade in said opening,cross member rmeans' extending across said opening from side each end ofthe cross member, each spring hinge having its upper end attached to thecross member and its lower end attached to the damper blade whereby theweight of the damper blade is carried .by the Spring hinges in tension,and ar- "bua'te means adjacent the spring hinges for limiting thecurvature thereof.

'7. A draft stabilizer adapted to be mounted in an air passage leadingto the interior of a furnace flue, comprising, a frame, a-swingableshutter, a hinge-support stationarily fixed to the frame adjacent theouter facewof the shutter, and a pair .of

laterally spaced hinges formed of thin, fiat spring steel, each of saidhinges being fixed at one end to the hinge-support, and fixed at itsothenend to the outer face of the shutter, whereby the shut ter may beswung from a'vertical position to an angular position with relation'tothe .frame,'each of said hinges being longitudinally curved when theshutter has been swung to an angular position, said frame having anair'ppening controlled by the shutter, and said hinge-support spanningsaid air Opening above the bottom edge thereof.

8. -A draft stabilizer adapted to bemounted in an air passagewayleading; to the interior-of a furnace flue, comprising aframe, aswingable shutter, a hinge-support stationarily fixed to the frameadjacent the outer face of the shuttenand a pair of laterally spacedhinges formed'of thin, fiat spring steel, each of said hinges beingfixed at one end to the-hinge-suppor-t, and fixed at its other end tothe outer face of shutter, whereby the shutter may be swung from avertical position to an angular position with relation to the frame, thetop end of each hinge being fixed in the hinge-support and the bottomend of each hinge being fixed to the shutter at intermediate portions ofthe shutter. l

- MORRIS W. CREW.

REFERENCES CI TED The following references are of 'record .in the fileof this patent: v

I UNITED STATES PATENTS v Date I Switzerland .Dec. 16.. 1938

